313. Here's How Real Adversaries Abuse PowerShell for Discovery

Hello everyone!

Today we'll look at another example of PowerShell abuse. And this time we'll talk about the Discovery tactic.

So, let's look into the report on Gootloader. There're multiple interesting examples of PowerShell abuse.

The adversary uses it to search for accounts with SPNs:

powershell.exe  -command "$search = New-Object DirectoryServices.DirectorySearcher([ADSI]''); $search.Filter = '(&(servicePrincipalName=*)(objectCategory=user))'; $results = $search.FindAll(); foreach ($result in $results) { $u = $result.GetDirectoryEntry(); Write-Host $u.name, $u.samaccountname; foreach ($s in $u.servicePrincipalName) { Write-Host $s; } Write-Host '---'; }"

Finds computers where the current user has admin rights:

powershell.exe  -ExecutionPolicy bypass -Command "$UBcPGBjR99={param($vars);$nZzkzLTK99=$vars.computer;$Error.clear();Get-WmiObject -Class Win32_OperatingSystem -ComputerName $nZzkzLTK99 -ErrorAction SilentlyContinue;$SBUXiYcH99=$error[0];$out='';if($SBUXiYcH99 -eq $null){$out='Local Admin access on: $nZzkzLTK99';}elseif(-not $SBUXiYcH99.Exception.Message.Contains(\"Access is denied.\")){}else{}$out;};$YSUPVCAn99=New-Object System.DirectoryServices.DirectorySearcher;$YSUPVCAn99.SearchRoot=New-Object System.DirectoryServices.DirectoryEntry;$YSUPVCAn99.Filter='(&(sAMAccountType=805306369))';$zcGEXXZD99=$YSUPVCAn99.FindAll()|%{$_.properties.dnshostname};$rsp=[runspacefactory]::CreateRunspacePool(1,100);$rsp.CleanupInterval=New-TimeSpan -Seconds 10;$rsp.open();$jobs=New-Object System.Collections.ArrayList;$i=0;while($i -lt $zcGEXXZD99.Count){$nZzkzLTK99=$zcGEXXZD99[$i];if($rsp.GetAvailableRunspaces() -gt 0){$vars=[PSCustomObject]@{'computer'=$nZzkzLTK99};$PS3=[PowerShell]::Create();$PS3.AddScript($UBcPGBjR99).AddArgument($vars)|Out-Null;$PS3.RunspacePool=$rsp;$jobs+=[PSCustomObject]@{Pipe=$PS3;Status=$PS3.BeginInvoke()};$i++;}else{Sleep -Milliseconds 500;}}while($jobs.Status.IsCompleted -notcontains $true){Sleep -Milliseconds 500;}foreach($job in $jobs){Write-Host $($job.Pipe.EndInvoke($job.Status));$job.Pipe.Dispose();}$rsp.Close();$rsp.Dispose();"

Enumerates all Windows Server machines:

powershell  -NoProfile -Command "Write-Host '===== SERVERS ====='; try { $s=New-Object DirectoryServices.DirectorySearcher; $s.Filter='(objectCategory=Computer)'; 'name','dnshostname','operatingsystem','lastlogontimestamp'|%{$s.PropertiesToLoad.Add($_)}; $s.PageSize=5000; $c=0; $s.FindAll()|%{ if($_.Properties['operatingsystem'] -match 'Windows Server') { $n=$_.Properties['name']; $d=$_.Properties['dnshostname']; $o=$_.Properties['operatingsystem']; $l=if($_.Properties['lastlogontimestamp']) { [datetime]::FromFileTime($_.Properties['lastlogontimestamp'][0]) } else { 'N/A' }; Write-Host \"$n, $d, $o, $l\"; $c++ } }; Write-Host \"nCount of all Windows Servers: $c\" } catch { Write-Host \"nError: $($_.Exception.Message)\" }"

As you can see, in all cases the adversary creates a DirectorySearcher object to query Active Directory. We can use it to build our query:

event_type: "processcreatewin"

AND

proc_file_path: "powershell.exe"

AND

cmdline: "DirectorySearcher"

See you tomorrow!

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